When March Kelleher, the leftwing, paranoid blogger in Bleeding Edge, invites the heroine, Maxine Tarnow, to recall "what Susan Sontag always sez", Maxine responds: "I like the streak, I'm keeping it?" But March – the novel's voice of misguided sincerity – persists, correcting her: "If there's a sensibility you really want to talk about, and not just exhibit it yourself, you need 'a deep sympathy modified by contempt'." Sontag's idea strikes at the heart of what Thomas Pynchon has undertaken in Bleeding Edge. It prompts a question relevant to him and to all contemporary artists, from writers to directors to choreographers: if the present day is atomised, paranoid, infantile, obsessive, can a work of art capture this without taking on these attributes itself?

Bleeding Edge is a multi-character detective(-ish) story, set in 2001 in a New York thrumming with ventures linked to Silicon Alley, the home of Manhattan's tech companies. Its concerns are momentous: 9/11 – which takes place just over halfway through – the internet, and the price of capitalism. Add to this thematic weight the fact that Pynchon invokes the tones of multiple genres – detective story, chick lit, teen lit, sci-fi, Tom Wolfean social satire – and the fact that it takes almost 500 pages, most of them frantic with pop-culture references, to unfold, and a sense emerges of the scale of investment Pynchon demands from his reader. Like a major bank, like a marriage, Bleeding Edge is an idea too big to fail – at least, not without grand-scale disillusionment.

As if this had burdened Pynchon with the task of keeping the investors sweet, he supplies regular perks external to the story, mainly in the form of intellectual flattery. "All night long, not a shadow in the neighbourhood. Talk about nessun dorma," is a typical invocation: it requires no understanding of the allusion, but invites the reader to bask in a sense of shared refinement. "I have always depended on the kindness of stranglers" is a gag designed to give the more bitter reader (who, again, needn't understand the line's real meaning) the thrill of cultural mastery – a sense of what it would be like to be so clever you can diss Tennessee Williams's sincerity at will.

The risk inherent in questioning the motive behind any joke, in suggesting that its value may be aggressive and its motivation cynical in nature, is that it seems to expose a fun-factor deficiency in the questioner. But, like the intellectual flattery, the pop-culture jokes in Bleeding Edge – there's an emphasis on the sitcom Friends in particular – are soon insulting. Pynchon aims his gags hyper-consciously at the point where he anticipates the reader's belief in her own sense of irony meets with her intellectual self-satisfaction, just at the safe (ie the unexamined) edge of a depressive nihilism which might get sad thrills laughing at Susan Sontag's hair. There is certainly contempt here – but what's beneath it doesn't seem a lot like sympathy.

Comparably shrewd is the humour aimed at a certain type of American Jewish reader, for whom Bleeding Edge is meant to be rich pickings throughout. But most of these jokes are cliches offered up with the wily confidence of a standup comic who knows he'll get a whoop just by naming the town he's performing in. When March says, "I gotta warn you, though, I'm not much into shopping for recreation," Maxine gasps: "But you… you are Jewish?" Later on, when another character says, "I've been going through such guilt", she's told: "If you're not Jewish, you have to have a licence, cause we hold the patent, see."

Bleeding Edge has a vagabond third-person narration – its perspective is sometimes Maxine's, sometimes no one's, and sometimes it sounds a lot like a male, American author commenting on things he doesn't like; the Hamptons, for example, are "a diseased fantasy". But a conceptually stable narrator would have prevented all the genre-hopping, which often takes place mid-scene. Within a detective-story chapter, for example, the relationship between Maxine and her friend Heidi prompts a jaunt into an ersatz teen novel: "Princess Heidrophobia is always the lead babe, while Lady Maxipad is the fastmouthed soubrette, the heavy lifter…"

An author might engineer genre shifts like this in order to convey more precisely the texture of a relationship, personality or scene, but in Bleeding Edge they are too often associated with an instant balloon-pop of integrity for this to seem like Pynchon's intention. Maybe they are no more than an expression of his backstage, cerebral fun – of the drunkenness of form being various.

Though it's hard to believe Pynchon has any interest in non-American readers, most of us have seen enough about America on film to know what he's getting at when he refers to "The Yupper West Side" of New York. (Even so, it's worth noting that such provincial references if they were made in regard to London, or Berlin, would be found meaningless by an American audience and therefore unpublishable.) But there are times when the lexicon and signifiers have a mean-girl exclusivity. When Maxine comments on the lavishness of a Halloween party, her friend Vyrva scoffs: "This? Next to the Alley a couple years ago? The average startup party? This is a footnote, my dear. Commentary."

Within the tangle of gags, there is a complex plot. When Maxine is hired as a private fraud investigator to check out Gabriel Ice, CEO of the computer security outfit, hashslingrz, the action takes place in cyberspace and "meatspace' – ie the real world. There are encounters between avatars online, there are guns, there are postmodern jokes gussied up as characters – and when, as it often does, the writing gleams with intuition and real wisdom, the madcappery seems all the more baffling and cheap. "The internet has erupted into a Mardi Gras for paranoids and trolls, a pandemonium of commentary there may not be time in the projected age of the universe to read all the way through," is one hint at the lyricism which might have been, throughout.

Another tantalising feature is Pynchon's gift for catching the rhythms of American speech. "A boat, how about a boat, they own a boat?"; or "Lemme at least buy yiz lunch"; or, when Maxine's therapist learns from Maxine that her ex-husband is "back", "Is that, like, air quotes, 'back' or just back?" – are three among numerous, moving examples. And in a novel so uninterested in characters, Horst Loeffler – Maxine's ex husband – is a joyful little hub of life. A trader with an office in the World Trade Centre, Horst is a man who eats his ice cream from the tub with two spoons, who gives his ex-wife multiple orgasms, a man who – in an eloquent quip at the expense of the American mind – thinks Inshallah is "Arabic for whatever".

No doubt a good genre book is worth more than a bad literary one any day, but when a writer with real genius squanders so much of his energy on clowning – and for an audience it's not at all clear he respects – it's worth asking what's going on. The idea that jokes are a defence against intimacy is a cliche – perhaps they can also be a defence against close reading.